Patent Foramen Ovale (PFO) Closure Device with Radial and Circumferential Support

ABSTRACT

The present invention provides a device for occluding an anatomical aperture, such as a septal defect or patent foramen ovale (PFO). The occluder includes two sides connected by an intermediate joint. Each of the sides includes at least one elongate element, which is arranged to form non-overlapping loops. Each loop has at least one radially-extending segment that is adjacent to a radially-extending segment of another loop. In at least some embodiments, at least one pair of adjacent radially-extending segments is connected. The loops of the device may be of various shapes, sizes, and configurations, and, in at least some embodiments, the loops have rounded peripheries. In some embodiments, at least one of the sides includes a tissue scaffold. When the occluder is deployed in vivo, the two sides are disposed on opposite sides of the septal tissue surrounding the aperture, thereby exerting a compressive force on the septal tissue that is distributed along both the outer periphery of the occluder and the radially-extending segments.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 12/210,897 filed Sep. 15, 2008, now issued as U.S. Pat. No.8,784,448; which is a continuation application of U.S. application Ser.No. 10/455,572 filed Jun. 5, 2003, now issued as U.S. Pat. No.7,431,729; which claims the benefit under 35 USC §119(e) to U.S.Application Ser. No. 60/386,327 filed Jun. 5, 2002, now expired. Thedisclosure of each of the prior applications is considered part of andis incorporated by reference in the disclosure of this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to an occlusion device for theclosure of physical anomalies like septal apertures, such as patentforamen ovale and other septal and vascular defects.

2. Background Information

A patent foramen ovale (PFO), illustrated in FIG. 1, is a persistent,one-way, usually flap-like opening in the wall between the right atrium11 and left atrium 13 of the heart 10. Because left atrial (LA) pressureis normally higher than right atrial (RA) pressure, the flap usuallystays closed. Under certain conditions, however, right atrial pressurecan exceed left atrial pressure, creating the possibility that bloodcould pass from the right atrium 11 to the left atrium 13 and bloodclots could enter the systemic circulation. It is desirable that thiscircumstance be eliminated.

The foramen ovale serves a desired purpose when a fetus is gestating inutero. Because blood is oxygenated through the umbilical cord, and notthrough the developing lungs, the circulatory system of a heart in afetus allows the blood to flow through the foramen ovale as aphysiologic conduit for right-to-left shunting. After birth, with theestablishment of pulmonary circulation, the increased left atrial bloodflow and pressure results in functional closure of the foramen ovale.This functional closure is subsequently followed by anatomical closureof the two over-lapping layers of tissue: septum primum 14 and septumsecundum 16. However, a PFO has been shown to persist in a number ofadults.

The presence of a PFO is generally considered to have no therapeuticconsequence in otherwise healthy adults. Paradoxical embolism via a PFOis considered in the diagnosis for patients who have suffered a strokeor transient ischemic attack (TIA) in the presence of a PFO and withoutanother cause of ischemic stroke. While there is currently no definitiveproof for a cause-effect relationship, many studies have confirmed astrong association between the presence of a PFO and the risk forparadoxical embolism or stroke. In addition, there is significantevidence that patients with PFO who have had a cerebral vascular eventare at increased risk for future, recurrent cerebrovascular events.

Accordingly, patients with an increased future risk are considered forprophylactic medical therapy to reduce the risk of a recurrent embolicevent. These patients are commonly treated with oral anticoagulants,which have the potential for adverse side effects, such as hemorrhaging,hematoma, and interactions with a variety of other drugs. The use ofthese drugs can alter a person's recovery and necessitate adjustments ina person's daily living pattern.

In certain cases, such as when anticoagulation is contraindicated,surgery may be necessary or desirable to close the PFO. The surgerywould typically include suturing a PFO closed by attaching septumsecundum to septum primum. This sutured attachment can be accomplishedwith either an interrupted or a continuous stitch and is a common way asurgeon shuts a PFO under direct visualization.

Umbrella devices and a variety of other similar mechanical closuredesigns, developed initially for percutaneous closure of atrial septaldefects (ASDs), have been used in some instances to close PFOB. Thesedevices have the potential to allow patients to avoid the potential sideeffects often associated with anticoagulation therapies and the risks ofinvasive surgery. However, umbrella devices and the like that aredesigned for ASDs are not optimally suited for use as a PFO closuredevice.

Currently available designs of septal closure devices present drawbacks,including technically complex implantation procedures. Additionally,there are not insignificant complications due to thrombus, fractures ofthe components, conduction system disturbances, perforations of hearttissue, and residual leaks. Many devices have high septal profile andmay include large-masses of foreign material, which may lead tounfavorable body adaptation of a device. Since ASD devices are designedto occlude a hole, many lack anatomic conformability to the PFOflap-like anatomy. That is, when inserting an ASD device to close a PFO,the narrow opening and the thin flap may form impediments to properdeployment. Even if an occlusive seal is formed, the device maybedeployed in the heart on an angle, which could leave some components notsecurely seated against the septum, thereby risking thrombus formationdue to hemodynamic disturbances. Finally, some septal closure devicesare complex to manufacture, which may result in lack of consistency inproduct performance.

The present invention is designed to address these and otherdeficiencies of the prior art septal closure devices.

SUMMARY OF THE INVENTION

The present invention provides a device for occluding an anatomicalaperture, such as a septal defect or a PFO. This occluder includes twosides connected by an intermediate joint. Each of the sides includes atleast one wire or other elongate element for structural support(referred to collectively as “wire”), which is arranged to formnon-overlapping loops. Each loop has at least one radially-extendingsegment that is adjacent to a radially-extending segment of anotherloop. In at least some embodiments, at least one pair of adjacentradially-extending segments is connected. The loops of the device may beof various shapes and sizes. In at least some embodiments, the loopshave rounded peripheries. The configuration of the loops and sides ofthe occluder are varied according to different embodiments of theinvention. In some embodiments, at least one of the sides includes atissue scaffold.

The wires forming the occluders of the present invention may beconstructed of various biocompatible materials. In some embodiments, thewires are formed of shape memory materials, e.g., nitinol. In otherembodiments, the wires are formed of polymers, bioabsorbable polymers,or combinations thereof.

The occluder according to the present invention is designed such that,when deployed in vivo, the two sides are disposed on opposite sides ofthe septal tissue surrounding the aperture, i.e., septum primum andseptum secundum. Thus, the two sides exert a compressive force on theseptal tissue that is distributed along both the outer periphery of theoccluder and the radially-extending segments. In at least someembodiments, the radially-extending segments increase the stiffness ofthe occluder, thereby preventing the occluder from becoming dislodgedfrom its intended delivery site. In at least some embodiments, theflexible, rounded peripheries of the loops prevent the occluder frominflicting trauma upon the septal tissue as the heart contracts. In atleast some embodiments of the present invention, the occluder isrepositionable and/or retrievable. These and other advantageous featuresof the present invention will be explained in more detail in connectionwith the following illustrations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a human heart including a septaldefect;

FIG. 2 is a top view of an occluder according to one embodiment of theinvention;

FIG. 3 is a front elevational view of the distal side of the occluder ofFIG. 2;

FIG. 4 is a front elevational view of the proximal side of the occluderof FIG. 2;

FIG. 5 is a front elevational view of the occluder of FIG. 2;

FIGS. 6A and 6B are a side view and a front elevational view,respectively, of an occluder according to another embodiment of thepresent invention;

FIG. 7 is a side elevational view of the occluder of FIGS. 6A and 6Bdeployed in vivo;

FIG. 8 is a front elevational view of the distal side of an occluderaccording to a further embodiment of the present invention;

FIG. 9 is a front elevational view of the proximal side of an occluderaccording to still another embodiment of the present invention;

FIGS. 10A, 10B, 10C and 10D are front elevational views of variousembodiments of the proximal side of an occluder according to the presentinvention;

FIG. 11 is a front elevational view of the distal side of an occluderaccording to yet another embodiment of the present invention;

FIG. 12 is a front elevational view of a proximal side of an occluderaccording to the present invention that includes a tissue scaffold;

FIGS. 13A, 13B and 13C are perspective, side elevational, and sideelevation in vivo views, respectively, of an occluder according to yet afurther embodiment of the present invention;

FIGS. 14A, 14B, 14C, 14D and 14E are side elevational views of onemethod for delivering an occluder according to the present invention toa septal defect;

FIGS. 15A, 15B, 15C, 15D and 15E are side elevational views of a secondmethod for delivering an occluder according to the present invention toa septal defect;

FIG. 16 is a side elevational view of a partially-deployed occluderaccording to the present invention;

FIGS. 17A, 17B, 17C and 17D are side elevational views of one method forretrieving an occluder according to the present invention from a septaldefect; and

FIG. 18 is a side elevational view of a second method for retrieving anoccluder according to the present invention from a septal defect.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a device for occluding an aperture withinbody tissue. In particular and as described in detail below, theoccluder of the present invention may be used for closing a PFO in theatrial septum of a heart. Although the embodiments of the invention aredescribed with reference to a PFO, one skilled in the art will recognizethat the device and method of the present invention may be used to treatother anatomical conditions. As such, the invention should not beconsidered limited to any particular anatomical condition.

FIG. 1 illustrates a human heart 10, having a right atrium 11 and a leftatrium 13. The atrial septum 12 includes septum primum 14, septumsecundum 16, and a passage 18 between the right 11 and left 13 atria.The anatomy of the septum varies widely within the population. In somepeople, septum primum 14 extends to and overlaps with septum secundum16. The septum primum 14 may be quite thin. When a PFO is present, thereis a chance that blood could travel through the passage 18 betweenseptum primum 14 and septum secundum 16 (referred to as “the PFOtunnel”).

An occluder according to one embodiment of the present invention isshown in FIGS. 2 through 7. As shown in FIG. 2, the occluder 20 includesa distal side 30 (FIG. 3) and a proximal side 40 (FIG. 4). In thisapplication, “distal” refers to the direction away from a catheterinsertion location and “proximal” refers to the direction nearer theinsertion location. Distal side 30 and proximal side 40 are connected byintermediate joint 22. As shown in FIG. 7, the occluder 20 may beinserted into the septal tissue 12 to prevent the flow of blood throughthe passage 18, i.e., the occluder may extend through the PFO tunnel 18such that the distal side 30 is located in the left atrium 13 and theproximal side 40 is located in the right atrium 11. Various features ofthe occluder 20 will be described with reference to FIGS. 2 through 7.

The occluder 20 is constructed of wire or other elongate element forstructural support, referred to collectively as “wire” 25. The wire isarranged to form loops in both the distal 30 and proximal 40 sides ofthe occluder 20. According to some embodiments of the present invention,several wires 25 are used to construct the occluder 20. According toother embodiments, the occluder may be formed of a tube using, forexample, an etching or cutting process to create elongate members. Theelongate members have the general structure of a wire, i.e., long andthin, but are not necessarily round. As used herein, the term “wire” isintended to encompass wires and elongate members (whether or not formedby an etched tube).

The wire(s) 25 may be formed of various biocompatible materials. In atleast some embodiments, the occluder 20 is formed of shape memorymaterial (e.g., nitinol). The thermal shape memory and/or superelasticproperties of shape memory materials, e.g., nitinol, permit the occluder20 to resume and maintain its intended shape in vivo despite beingdistorted during the delivery process. In particular embodiments, theoccluder 20 is formed of nitinol that is austenitic at body temperature.Alternatively, or additionally, the occluder 20 may be formed of otherhigh-strength super-alloys, such as Hastelloy® (available from HaynesInternational), Elgiloy®, or MP35N. In still other embodiments, occluder20 may be formed of a polymer (e.g., plastics), bioabsorbable polymer,or combination of the foregoing.

The distal side 30 of the occluder 20 (also called the “anchor portion”)is shown in FIG. 3. The distal side 30 includes three loops 32 a, 32 b,and 32 c, collectively referred to as loops 32. As illustrated, theloops 32 are evenly distributed about and held together at center joint22. Each of loops 32 has six sides of roughly the same linear dimension.Each of loops 32 has at least one segment that is adjacent to a segmentof another of loops 32. Specifically, segment 33 a of loop 32 a isadjacent to segment 31 b of loop 32 b; segment 33 b of loop 32 b isadjacent to segment 31 c of loop 32 c; and segment 33 c of loop 32 c isadjacent to segment 31 a of loop 32 a.

Although the distal side 30 of the occluder 20 shown in FIG. 3 includesthree loops 32, occluders according to the present invention may includeany number of loops 32 necessary for a given application. Occludershaving less than or equal to ten loops 32 may be formed withoutrequiring significant adjustments. In general, the stiffness of theoccluder 20 increases as the number of loops 32 increases. However,occluders having more than ten loops 32 may be complicated tomanufacture and deliver through the vasculature. Whatever the number ofloops chosen, the loops 32 may be of varied sizes to facilitatedelivery, e.g., to improve collapsibility of the occluder 20 or toenhance securement at the delivery site. For example, loops 32 sized tobetter conform with anatomical landmarks will provide enhancedsecurement of the occluder 20 to the septal tissue 12 in vivo.

Regardless of the number of loops included in distal side 30, the outershape of the loops 32 may vary. For example, as illustrated in FIG. 3,the loops 32 may be hexagonal with 120 degree angles at their bends(i.e., “blunt loops”). Alternatively, or additionally, the non-adjacentwire segments may be rounded to provide for a smoother perimeter. As thenumber of loops 32 in the distal side 30 of occluder 20 increases, itbecomes desirable to round the outer perimeters of the loops 32 so as toprevent the infliction of trauma on the surrounding septal tissue 12.The loops 32 may also be formed as concave structures, such that theoutermost portions of the loops 32 of the distal side 30 oppose theoutermost portions of the loops 42 of the proximal side 40, as describedin more detail below, thereby creating a desirable opposing force thatsecures the occluder 20 at its desired location in vivo.

As previously mentioned, the wires 25 forming loops 32 are attached atcenter joint 22. The adjacent segments extend radially outward fromcenter joint 22 at a spacing of approximately 120 degrees apart. Thearea of septal tissue enclosed by loops 32 provides support for thedistal side 30 once the occluder 20 is deployed in vivo. In at least oneembodiment of the present invention, a connection is provided betweenthe adjacent segments, e.g., between segments 33 a and 31 b, betweensegments 33 b and 31 c, and between segments 33 c and 31 a. For example,as shown in FIG. 3, the adjacent segments may be connected by welds 38.Such connections provide additional stiffness to the occluder 20 andhelp secure the occluder 20 at its desired location in vivo, asdescribed in more detail below.

The adjacent segments may be connected in a variety of ways. Aspreviously indicated, the adjacent segments may be welded. The length ofthe welds 38 may extend along less than the entire radial distance ofthe adjacent segments. Alternatively, the adjacent segments may beconnected with a tube, e.g., a hypo tube, having a smaller diameter thanthe diameter of the coupled adjacent segments. In such a configuration,the tube holds the segments together by exerting a compressive forceagainst the wires. Numerous additional means of connecting the segmentswill be apparent to those skilled in the art, e.g., glue, clips,sutures, polymer sleeves, etc., and are considered to be within thescope of the present invention.

As previously indicated, the connections, e.g., welds 38, betweenadjacent segments provide stiffness to the distal side 30 of theoccluder 20. As illustrated in FIG. 3, the welds 38 may extend asignificant distance along the length of the adjacent segments or mayextend along only a portion of the adjacent segments. Withoutconnections between the adjacent segments, a force on any of loops 32will be borne by that loop alone, and the stiffness of the distal side30 is diminished. The capacity to vary the stiffness of the distal side30 using various numbers and types of connections provides significantadvantages. Thus, for some applications of the present invention, it maybe desirable to include connections between some adjacent segments butnot others or to vary the radial distance that the connections extendand/or the placement of the connections relative to the center joint 22.As the distance that the connections, e.g., welds 38, extend increases,the distal side 30 becomes stiffer. When the connections extend alongless than half of the radial distance, the stiffness of the distal side30 is diminished. The location of welds 38 also affects the stiffness ofthe occluder 20. For example, a shorter weld 38 placed at a moreradially outward location along the adjacent segments will increase thestiffness and dislodgement resistance of the occluder 20. In at leastsome embodiments of the present invention, the connections, e.g., welds38, extend along the entire length of the adjacent segments.

It should be noted that the inclusion of connections, e.g., welds 38, toincrease the stiffness of the distal side 30 necessitates the use of agreater force to maintain the occluder 20 in reduced profile (i.e., indelivery configuration). The delivery system for an occluder 20including distal side 30 having connections, e.g., welds 38, must,therefore, possess greater radial strength to contain such aconfiguration.

The proximal side 40 of the occluder 20 is shown in FIG. 4. The proximalside 40 includes six loops, 42 a-42 f, collectively referred to as loops42. The loops 42 are evenly distributed about tip 44. Tip 44 may be aweld, solder, or tube into which the wires would fit. Each of loops 42is formed of wire segments that extend radially outward from tip 44,bend approximately 180 degrees, and then extend back to intermediatejoint 22. Thus, one end of each of loops 42 is attached to tip 44, whilethe other end of each of loops 42 is attached to intermediate joint 22.As a result, the axial position of each of loops 42 in proximal side 40is slightly offset.

The wires forming each of loops 42 do not overlap, i.e., they are notintertwined or weaved. In at least one embodiment, illustrated in FIG.5, the radially-extending segments of the proximal side 40 are rotated,for example, 60 degrees with respect to the radially-extending segmentsof the distal side 30. Thus, as shown in FIG. 5, the proximalradially-extending segments 41 a, 43 b, 41 c, 43 d, 41 e, and 43 f,which depart from intermediate joint 22 are rotated 60 degrees (asindicated by angle φ) with respect to distal radially-extending segments31 a, 33 a, 31 b, 33 b, 31 c, and 33 c. Further, the loops 42 ofproximal side 40 maybe flat, while the loops 32 of distal side 30 may beconcave, as previously described. Upon deployment in vivo, the opposingcompressive forces exerted by the sides 30 and 40 on the septal tissue12 are particularly advantageous.

Although the proximal side 40 of the occluder 20 shown in FIG. 4includes six loops 42, one skilled in the art will recognize that theproximal side 40 of an occluder according to the present invention mayinclude any number of loops 42 required for a given application.However, in view of the fact that the loops 42 are non-overlapping, itmay not be practical to include more than ten loops 42 in proximal side40.

In a manner similar to that described above with regard to the distalside 30, loops 42 of proximal side 40 also include adjacent segmentsthat may be connected. Specifically, segment 43 a of loop 42 a isadjacent to segment 41 b of loop 42 b; segment 43 b of loop 42 b isadjacent to segment 41 c of loop 42 c; segment 43 c of loop 42 c isadjacent to segment 41 d of loop 42 d; segment 43 d of loop 42 d isadjacent to segment 41 e of loop 42 e; segment 43 e of loop 42 e isadjacent to segment 41 f of loop 42 f; and segment 43 f of loop 42 f isadjacent to segment 41 a of loop 42 a. Connections maybe includedbetween any or all of the adjacent segments. The adjacent segments maybe connected using any of the connection means previously described,e.g., welds 48. For example, as shown in FIG. 4, welds 48 are locatedbetween each pair of adjacent segments. Alternatively, as shown in FIG.9, welds 98 are located between adjacent segments that are spaced 120degrees apart, i.e., between segments 43 b and 41 c, between segments 43d and 41 e, and between segments 43 f and 41 a. In preferredembodiments, welds are typically located on those adjacent segmentsextending from intermediate joint 22, such that the segments contactingthe septal tissue 12 in the right atrium 11 are stiffest. Furthermore,including connections between at least those adjacent segments thatcontact the septal tissue minimizes fretting and the possibility ofcorrosion due to metal rubbing against metal.

As indicated previously and shown in FIG. 2, distal side 30 and proximalside 40 of occluder 20 are connected by intermediate joint 22. Theintermediate joint 22 secures the wires of the device and, according tosome embodiments, may be a weld, solder or tube. If a tube is used, thetube may have a diameter slightly less than that of the collected wires,such that the tube may be expanded during delivery and then returned toits reduced diameter following deployment of the occluder 20 in vivo.The reduced diameter tube will secure the wires forming loops 32 and 42into the tube. A tube capable of expanding and reducing may beconstructed of a shape memory material, e.g., nitinol. Alternatively,the intermediate joint 22 may be a tube having a diameter larger thanthat of the collected wires; following deployment of the occluder 20 invivo, this tube may be crimped to secure the wires forming loops 32 and42.

In other embodiments of the present invention, the intermediate joint 22may be a spring, e.g., a coil spring. According to these embodiments,the spring is designed to pull the proximal side 40 of occluder 20closer to the distal side 30, thereby compressing the septal tissue 12between the distal 30 and proximal 40 sides in vivo. The tension of thespring may be selected such that the occluder 20 accommodates septaltissue of varying thicknesses. When considering the characteristics ofthe spring, the need to accommodate septal tissue of varying thicknessesand the need to provide sufficient (but not too much) compressive forcemust be balanced. One skilled in the art will be capable of selecting aspring meeting these criteria for a given application.

In still further embodiments of the present invention, intermediatejoint 22 is positioned at an angle 0, as shown in FIG. 6. Often,anatomical anomalies have non-perpendicular apertures and are sometimesquite significantly non-perpendicular. Thus, the occluder 20 may includean angled intermediate joint 22, such that the angle of the anatomicalaperture is more closely matched by the pre-formed angle 0 of theoccluder 20. Accordingly, the distal 30 and proximal 40 sides ofoccluder 20 are more likely to be seated against and minimize distortionto the septal tissue 12 surrounding the passage 18. A well-seatedoccluder 20 is less likely to permit blood leakage between the right 11and left 13 atria, and the subject into which the occluder 20 has beenplaced is, therefore, less likely to suffer embolisms and other adverseevents. Advantageously, angled intermediate joint 22 also facilitatesdelivery of occluder 20, as described in more detail below, because itis angled toward the end of the delivery catheter. In at least someembodiments, the angle 0 is about 0-45 degrees off the plane created bythe proximal side 40. One skilled in the art will recognize that theconcept of an angled intermediate joint may also be applied to septaloccluders other than those disclosed herein.

When intermediate joint 22 is positioned at angle 0, distal side 30 andproximal side 40 of occluder 20 may be configured such that they areeither directly opposing or, as shown in FIGS. 6A and 6B, offset bydistance A. One skilled in the art will, of course, recognize that theconfiguration of either or both of distal side 30 and proximal side 40may be adjusted such that the compressive forces applied by the distal30 and proximal 40 sides of occluder 20 are as directly opposing aspossible. However, in some clinical applications, an occluder 20 havingan offset of distance A may be particularly desirable. For example, asshown in FIG. 7, if the septal tissue 12 surrounding passage 18 includesa disproportionately thick portion (e.g., septum secundum 16 as comparedto septum primum 14), the offset may be used to seat occluder 20 moresecurely upon septal tissue 12. Moreover, the offset A allows each ofsides 30 and 40 to be centered around each side of an asymmetric defect.

When an intermediate joint 22 at angle 0 is included in occluder 20, amarker is required to properly orient the occluder 20 in its intended invivo delivery location. For example, platinum wire may be wrapped aroundone of loops 32 or 42 so as to permit visualization of the orientationof the occluder 20 using fluoroscopy. Alternatively, other types ofmarkers may be used, e.g., coatings, clips, etc. As will be readilyunderstood by one skilled in the art, the orientation of anon-symmetrical occluder 20 during delivery is of great importance. Ofcourse, when a non-symmetrical occluder 20 is used, the periphery of theoccluder 20 may be configured such that the clamping force applied bythe proximal side 40 is directly opposed to that applied by the distalside 30.

Upon deployment in vivo (a process described in detail below), anoccluder according to the present invention applies a compressive forceto the overlapping layers of septal tissue 12, i.e., septum primum 14and septum secundum 16. Distal side 30 is seated against the septaltissue 12 in the left atrium 13; joint 22 extends through passage 18;and proximal side 40 is seated against the septal tissue 12 in the rightatrium 11. As illustrated in FIGS. 2, 5, and 7, the proximal 40 anddistal 30 sides of occluder 20 overlap significantly, such that septumprimum 14 and septum secundum 16 are “sandwiched” between them once theoccluder 20 is deployed. The connected, adjacent segments provide aradially-extending compressive force, while the peripheral loops 32 and42 provide a circumferential compressive force. Thus, the compressiveforces are more evenly and more widely distributed across the surface ofthe septal tissue 12 surrounding the PFO. The unique combination ofradially-extending, connected, adjacent segments and peripheral loops 32and 42, therefore, provides the occluder 20 with superior dislodgementresistance as compared to prior art devices. As used herein,“dislodgement resistance” refers to the ability of an occluder 20 toresist the tendency of the force applied by the unequal pressuresbetween the right 11 and left 13 atria (i.e., the “dislodging force”) toseparate the occluder 20 from the septal tissue 12. Generally, a highdislodgement resistance is desirable.

Moreover, loops 32 and 42 are configured to provide occluder 20 withadequate surface area to seal the PFO. For example, the broadconfiguration of loops 32 and 42 increases the surface area of occluder20. Thus, loops 32 and 42 provide sealing along a large circumferencearound the passage 18 (i.e., the PFO), thereby minimizing thepossibility of leakage between the right 11 and left 13 atria.

While configured to provide sufficient circumferential sealing, loops 32and 42 are also configured to minimize the trauma they inflict on theseptal tissue 12 surrounding the PFO. Specifically, two features ofloops 32 and 42 achieve this. First, the peripheries of loops 32 and 42may be rounded. Second, the peripheries of loops 32 and 42 are formed ofa single wire and are, therefore, more flexible than theinteriorly-located, connected, adjacent segments, which are formed oftwo wires. These features minimize the overall trauma inflicted byoccluder 20 on the septal tissue 12 surrounding the PFO. Accordingly,occluder 20 has a low compression resistance. As used herein,“compression resistance” refers to the ability of an occluder 20 toresist the lateral compressive force applied by the heart as itcontracts during a heartbeat. Generally, an occluder that resistscompressive force, i.e., has high compression resistance, is undesirablebecause its rigid configuration may cause trauma to the septal tissue12, the right atrium 11, and/or the left atrium 13.

In heretofore known occluder designs, dislodgement resistance mustusually be sacrificed in order to improve, i.e., minimize, compressionresistance. However, the occluder 20 according to the present inventionpossesses both increased dislodgement resistance and minimizedcompression resistance. These desirable attributes are achieved by theunique combination of radially-extending, connected, adjacent segmentsand peripheral loops 32 and 42 discussed above. The radially-extending,connected, adjacent segments (i.e., struts) increase the stiffness and,correspondingly, the dislodgment resistance of the occluder 20. Theatraumatic shape of the peripheral loops 32 and 42 decreases thecompression resistance of the occluder 20. In effect, because the strutsare formed of double-stranded wire and the peripheries of the loops 32and 42 are formed of single-stranded wire, the center of the occluder 20is twice as strong as its parameter. This, correspondingly, produces theadvantageous combination of increased dislodgement resistance andminimized compression resistance in occluder 20.

The dislodgement resistance of occluder 20 may be further increasedwithout increasing the compression resistance by the inclusion ofadditional struts. As illustrated in FIG. 8, additional struts 85 a-85c, collectively referred to as additional struts 85, may be includedbetween loops 32 a-32 c, i.e., between adjacent segments 33 a and 31 b,33 b and 31 c, and 33 c and 31 a. Additional struts 85 may be of anysuitable diameter, and, according to some embodiments, the diameter ofadditional struts 85 may vary along their length. For example, thediameter of additional struts 85 may increase as the additional struts85 extend from intermediate joint 22 to the periphery of loops 32.Although FIG. 8 depicts additional struts 85 between loops 32 of distalside 30, additional struts 85 may additionally or alternatively beincluded between loops 42 of proximal side 40 of occluder 20.

The configuration of the occluder 20 according to the present inventionprovides several further advantages. First, broad loops 32 and 42 createa large surface area for occluder 20 and thereby anchor the occluder 20more securely in vivo. In contrast, many previously known occludersinclude narrow loops, which afford less surface area for exertion ofcompressive forces and secure placement of the occluder 20. Second, theloops 32 and 42 create an occlusion perimeter that likely extendssignificantly beyond the passage 18. Third, loops 32 and 42 arenon-overlapping, i.e., the wires are not intertwined or weaved. Thisnon-overlapping configuration reduces the occurrence of frettingcorrosion, which frequently occurs in prior art devices containingoverlapping wires.

Occluder 20 may be modified in various ways. According to someembodiments of the present invention, loops 32 of distal side 30 andloops 42 of proximal side 40 may be formed in a variety of shapes. Fourexamples are illustrated in FIGS. 10A-10D. For convenience, only theproximal side 40 of each of these modified embodiments is depicted.However, the distal side 30 of occluder 20 may be similarly modified.The star-shaped pattern 100 a shown in FIG. 10A includes four largeloops, referred to collectively as loops 102 a. Loops 102 a are centeredand approximately equally spaced around tip 44. Any or all of loops 102a may include a smaller loop, collectively referred to as loops 104 a,at their radial extent. Smaller loops 104 a may be capable of receivinga suture to facilitate retrieval of the occluder 20.

An alternative, diamond pattern 100 b is shown in FIG. 10B. Diamondpattern 100 b includes six diamond-shaped loops, referred tocollectively as loops 102 b, which are equally spaced around tip 44.Diamond pattern 100 b is asymmetrically oriented, such that two of loops102 b extend further in the radial direction than the other loops 102 b.This asymmetry may provide more complete and secure coverage of passage18 than that provided by a symmetric occluder 20. The asymmetric pattern100 b may also facilitate the compact, percutaneous delivery of occluder20.

Still a further alternative, rectangular pattern 100 c, is shown in FIG.10C. Rectangular pattern 100 c includes four rectangular-shaped loops,referred to collectively as loops 102 c, which are equally spaced aroundtip 44. Rectangular pattern 100 c provides extended coverage in twodirections. Such a rectangular shape may be particularly suited forcoverage of certain passages 18. Loops 102 c may extend further ineither the horizontal or vertical direction. As shown in FIG. 10C, loops102 c extend further in the horizontal direction.

Yet a further alternative, diamond pattern 100 d, is shown in FIG. 10D.Diamond pattern 100 d includes four diamond-shaped loops, referred tocollectively as loops 102 d. Two of loops 102 d are larger than theother two loops 102 d. Thus, an extended amount of coverage maybeprovided across the passage 18 in either the horizontal or verticaldirection. As shown in FIG. 10D, extended coverage is provided in thehorizontal direction.

Of course, distal 30 and proximal 40 sides of occluder 20 may beconfigured in a combination of shapes and sizes depending on clinicalneeds presented by a given PFO. If required, the loops 102 in theillustrative patterns provided in FIGS. 10A-10D, may be rounded. Thenumber of loops in embodiments of either the distal 30 or proximal 40sides may be varied as necessary. As previously described, loops 102 inthe illustrative patterns provided in FIGS. 10A-10D include adjacentsegments, which may be connected by, e.g., welds 108 a-108 d,respectively. One skilled in the art will be able to identify theconfiguration(s) appropriate for a given clinical application.

According to further embodiments of the present invention, smaller loopsmay be included on distal side 30 and/or proximal side 40 of occluder 20to increase the compressive force applied in close proximity to passage18 (i.e., the PFO). As illustrated in FIG. 11, three smaller loops 115a-115 c, referred to collectively as smaller loops 115, are located ondistal side 30. Smaller loops 115 are centered and equally spaced aroundintermediate joint 22. Although smaller loops 115 a-115 c in FIG. 11correspond in number and alignment with loops 32 a-32 c, respectively,such correspondence is not required. Moreover, smaller loops 115 neednot lie entirely in the same plane as loops 32 or 42. Thus, smallerloops 115 may bend in a direction generally perpendicular to the planein which loops 32 or 42 lie. Smaller loops 115 may be attached only tointermediate joint 22 or, alternatively, may also be connected to theadjacent segments of loops 32. In still other embodiments, smaller loops115 may be located at the peripheries of loops 32 rather than connectedto intermediate joint 22. When the smaller loops 115 are located at theperipheries of loops 32, additional wire segments may be included withinloops 32 to connect the smaller loops 115 to the intermediate joint 22.One skilled in the art will be able to determine the preciseconfiguration of smaller loops 115 appropriate for a given clinicalapplication.

According to still further embodiments of the present invention and asillustrated in FIG. 12, distal side 30 and/or proximal 40 side ofoccluder 20 may include a tissue scaffold 125. Tissue scaffold 125ensures more complete coverage of passage 18 and promotes encapsulationand endothelialization of septal tissue 12, thereby further encouraginganatomical closure of septum primum 14 and septum secundum 16. Tissuescaffold 125 may be formed of any flexible, biocompatible materialcapable of promoting tissue growth, including but not limited topolyester fabrics, Teflon-based materials, ePTFE, polyurethanes,metallic materials, polyvinyl alcohol (PVA), extracellular matrix (ECM)or other bioengineered material, synthetic bioabsorbable polymericscaffolds, other natural materials (e.g., collagen), or combinations ofthe foregoing materials. For example, tissue scaffold 125 may be formedof a thin metallic film or foil, e.g., a nitinol film or foil, asdescribed in United States Patent Appln. No. 2003/0059640 (the entiretyof which is incorporated herein by reference).

Adjacent segments may be stitched to tissue scaffold 125 so as tosecurely fasten the scaffold 125 to occluder 20. For example, FIG. 12shows tissue scaffold 125 affixed to proximal side 40 of an occluderaccording to the present invention. Proximal side 40 includes six loops42 a-42 f, collectively referred to as loops 42. Adjacent segments 43 aand 41 b, 43 b and 41 c, 43 c and 41 d, 43 d and 41 e, 43 e and 41 f,and 43 f and 41 a are attached to tissue scaffold 125 by stitches 127.Stitches 127 increase the stiffness of occluder 20 without welding orsoldering. Additionally, when the adjacent segments of loops 42 areconnected to tissue scaffold 125, the adjacent segments of loops 42 maybe spaced apart a small distance (i.e., they need not necessarily beconnected). Altering the spacing of the adjacent segments of loops 42adjusts the stiffness of the occluder 20, which may be desirable incertain circumstances. One skilled in the art will be able to determinethose clinical applications in which the use of stitches 127 and/orspaced, adjacent segments is appropriate.

According to yet further embodiments of the present invention, theconfiguration of occluder 20 may be modified to produce the low-profileoccluder 130 shown in FIG. 13A. In this embodiment, the manufacturingprocess is modified to increase the force with which the distal 30 andproximal 40 sides urge toward one another. Specifically, duringmanufacture, distal 30 and proximal 40 sides of occluder 20 may becrossed over each other (as shown in FIG. 13B) prior to connecting theadjacent segments of loops 32 and 42 (i.e., while the occluder 20 is inan “unconstrained” state). This crossed-over configuration maybeachieved by, for example, using the shape memory properties of a shapememory material, such as nitinol, i.e., forcing, e.g., loops 42 d and 42e of proximal side 40 through loop 32 c of distal side 30 or vice versaand heat-setting the crossed-over shape. The crossed-over shape,therefore, becomes the predisposed position of occluder 20. Occluder 20is then returned to its original, non-crossed-over state, and theadjacent segments of loops 32 and 42 are connected. The connected,adjacent segments prevent loops 42 d and 42 e from passing through loop32 c, and occluder 20 is, consequently, no longer capable of assumingits predisposed position. However, loops 42 d and 42 e of proximal side42 still tend to bend toward distal side 30. The resulting occluder 130,shown in FIG. 13A, is of low profile. Further, occluder 130 exerts agreater compressive force on the septal tissue 12 when deployed in vivo(as shown in FIG. 13C) then at least some of the previously-describedembodiments of occluder 20. This increased compressive force maybedesirable in applications where the septal tissue 12 is particularlythin in one area, i.e., septum primum 14. The profile of occluder 130may be lowered even further by angling tip 44 such that it issubstantially parallel to proximal side 40 of occluder 130, as shown inFIG. 13A. Angled tip 44 also facilitates catheter delivery of occluder130 because angled tip 44 points toward the end of the deliverycatheter.

Finally, although occluders according to the present invention have beenheretofore described as including distal 30 and proximal 40 sides havingdifferent configurations, an occluder 20 according to the presentinvention may, alternatively, include distal 30 and proximal 40 sideshaving identical configurations. This identical design may provideseveral advantages, including ease of manufacture. Furthermore, any ofthe configurations described herein for either distal side 30 orproximal side 40 may be applied to either or both of distal side 30 andproximal side 40 of occluder 20.

An occluder as described herein may be delivered to a septal defectusing any of several suitable delivery techniques, two of which will bedescribed herein. In the first delivery technique, shown in FIGS.14A-14E, a delivery catheter 140 is used to deliver, e.g., occluder 20.Catheter 140 contains occluder 20 in its distorted, elongated form. Aspreviously mentioned, in at least some embodiments, occluder 20 isformed of a shape memory material, e.g., nitinol, such that occluder 20will resume its intended shape following deployment in vivo. As shown inFIG. 14A, delivery catheter 140 is first inserted into the right atrium11 of the subject's heart. Catheter 140 is next inserted between septumprimum 14 and septum secundum 16 (i.e., through passage 18, which, inthis embodiment, is the PFO tunnel) and into the left atrium 13 (FIG.14B). Distal side 30 of occluder 20 is then deployed into the leftatrium 13, as shown in FIG. 14C. Following deployment of distal side 30,the catheter 140 is withdrawn through the PFO tunnel and into the rightatrium 11, such that intermediate joint 22 is deployed through the PFOtunnel (FIG. 14D). Finally, proximal side 40 of occluder 20 is deployedinto the right atrium 11, and catheter 140 is withdrawn from the heart(FIG. 14E). Once deployed, occluder 20 rests within the septal defect,and the distal 30 and proximal 40 sides exert a compressive forceagainst septum primum 14 and septum secundum 16 in the left 13 and right11 atria, respectively, to close the PFO.

In a second delivery technique, shown in FIGS. 15A-15E, deliverycatheter 150 includes a needle 151 capable of puncturing septum primum14. As illustrated in FIG. 15A, septum primum 14 is long and thin andextends over septum secundum 16 in the left atrium 13. In some clinicalapplications, it may be advantageous to access the left atrium 13 bypuncturing septum primum 14 rather than inserting the occluder 20through the passage 18 between septum primum 14 and septum secundum 16.For example, some anatomical configurations include an extremely obliquepassage 18 between the right atrium 11 and the left atrium 13. Thus,according to this second delivery technique, delivery catheter 150includes a needle 151 on its distal end and contains occluder 20 in itsdistorted, elongated form. Catheter 150 is first inserted into the rightatrium 11 of the subject's heart (FIG. 15A). Next, as shown in FIG. 15B,needle 151 punctures septum primum 14, and catheter 150 enters the leftatrium 13. Needle 151 is then retracted, and distal side 30 of occluder20 is deployed into the left atrium 13 (FIG. 15C). Following deploymentof distal side 30, catheter 150 is withdrawn through septum primum 14and into the right atrium 11, such that intermediate joint 22 isdeployed through septum primum 14, as shown in FIG. 15D. Finally,proximal side 40 of occluder 20 is deployed into the right atrium 11,and catheter 150 is withdrawn from the heart (FIG. 15E). Once deployed,the distal 30 and proximal 40 sides of occluder 20 exert a compressiveforce against septum primum 14 and septum secundum 16 in the left 13 andright 11 atria, respectively, to close the PFO. When using this seconddelivery technique to deploy occluder 20, intermediate joint 22 shouldnot be angled, i.e., intermediate joint 22 should be perpendicular toboth the distal 30 and proximal 40 sides of the occluder 20.

FIG. 16 provides a more detailed representation of occluder 20 in itsintermediate configuration between its compressed and fully-deployedstates. As previously described, proximal side 40 of occluder 20includes wire(s) 25, which form connected, adjacent radially-extendingsegments and loops 42, and tip 44. During delivery of occluder 20, tip44 is attached to a delivery wire 161, in a manner known to thoseskilled in the art. When the proximal side 40 of occluder 20 is beingdeployed in the right atrium 11, the wire(s) 25 exit catheter 140 or 150first, followed by tip 44, and, finally, delivery wire 161. Onceoccluder 20 has been positioned, delivery wire 161 is then fullyretracted into the catheter 140 or 150 and the catheter is retracted outof the right atrium 11.

Delivery wire 161 may be used to reposition and/or retrieve occluder 20as shown in FIGS. 17A-17D. If, following partial or complete deployment,the clinician desires to reposition or retrieve occluder 20, tip 44maybe recaptured with delivery wire 161 in catheter 170, as shown inFIG. 17A. As delivery wire 161 and tip 44 are pulled back into catheter170, loops 42 of proximal side 40 fold back into their delivery (i.e.,compressed) configuration (FIG. 17B) and are constrained by catheter170. Catheter 170 is then advanced through passage 18 and delivery wire161 is further retracted, such that loops 32 of distal side 30 fold intotheir delivery configuration (FIG. 17C) and are constrained by catheter170. Catheter 170 containing retrieved occluder 20 is then withdrawnthrough passage 18, into the right atrium 11 (FIG. 17D), and out of theheart.

In some embodiments according to the present invention, occluder 20 maybe repositioned and/or retrieved using the alternative technique shownin FIG. 18. As previously described, an occluder 20 according to thepresent invention may include identical distal 30 and proximal 40 sides.Thus, for example, occluder 20 may include both distal 30 and proximal40 sides as depicted in FIG. 3. In such an embodiment, proximal side 40will not include a tip 44 for recovery by a delivery wire. Analternative method of retrieving the occluder is, therefore, required.In FIG. 18, occluder 20 has been delivered (according to either of thedelivery techniques described above) to the extent that proximal side 40has been deployed in the right atrium 11 but not released from catheter140. A thread 181, such as a suture, is attached to each of loops 42 onproximal side 40 of occluder 20. If the occluder 20 requiresrepositioning, then thread 181 maybe retracted and loops 42 will foldback into their delivery configuration, such that occluder 20 may berepositioned or, even, completely retrieved. Once occluder 20 has beendeployed correctly, thread 181 may be cut and removed via catheter 140.

One skilled in the art would recognize that the occluders describedherein may be used with anti-thrombogenic compounds, including but notlimited to heparin and peptides, to reduce thrombogenicity of theoccluder and/or to enhance the healing response of the septal tissue 12following deployment of the occluder in vivo. Similarly, the occludersdescribed herein may be used to deliver other drugs or pharmaceuticalagents (e.g., growth factors, peptides). The anti-thrombogeniccompounds, drugs, and/or pharmaceutical agents may be included in theoccluders of the present invention in several ways, including byincorporation into the tissue scaffold 125, as previously described, oras a coating, e.g., a polymeric coating, on the wire(s) forming thedistal 30 and proximal 40 sides of the occluder. Furthermore, theoccluders described herein may include cells that have been seededwithin tissue scaffold 125 or coated upon the wire(s) forming the distal30 and proximal 40 sides of the occluder,

One skilled in the art would recognize that occluders according to thisinvention could be used in occluding other vascular and non-vascularopenings. For example, the device could be inserted into a left atrialappendage or other tunnels or tubular openings within the body.

Having described preferred embodiments of the invention, it should beapparent that various modifications may be made without departing fromthe spirit and scope of the invention, which is defined in the claimsbelow.

What is claimed is:
 1. A method for occluding a defect in septal tissue,comprising: deploying an occluding device at a defect of the septaltissue, the occluding device comprising: a first side adapted to bedisposed on a distal side of septal tissue with a defect and a secondside adapted to be disposed on a proximal side of the septal tissue witha defect, the first side and second side being connected by anintermediate joint; said first and second sides adapted to occlude thedefect upon deployment of the device at a delivery location; and saidfirst and second sides each comprising at least one wire arranged toform non-overlapping adjacent loops that are held together at theintermediate joint and extend radially from a center axis upondeployment of the device; wherein said loops of said first and secondsides are adapted to exert a compressive force on opposing sides of theseptal tissue to occlude the defect; and, wherein further the secondside of the device further comprises a tip, and the wire of each loop ofthe second side extends radially outward from the tip, bends, and thenextends back to the intermediate joint.
 2. The method of claim 1,wherein each loop on a side has at least one radially-extending segmentthat is adjacent to a radially-extending segment of another loop on thatside along a radial distance of the adjacent radially-extendingsegments.
 3. The method of claim 2, wherein at least one pair ofadjacent radially-extending segments is connected along the radialdistance of the adjacent radially-extending segments.
 4. The method ofclaim 1, wherein said device is adapted to center around anasymmetrically-located defect.
 5. The method of claim 2, wherein said atleast one pair of adjacent radially-extending segments are welded. 6.The method of claim 1, wherein said device includes a material selectedfrom the group consisting of metals, shape memory materials, alloys,polymers, bioabsorbable polymers, and combinations thereof.
 7. Themethod of claim 6, wherein said device includes nitinol.
 8. The methodof claim 1, wherein said first side further comprises a tissue scaffold.9. The method of claim 8, wherein said tissue scaffold includes amaterial selected from the group consisting of polyester fabrics,Teflon-based materials, polyurethanes, metals, polyvinyl alcohol (PVA),extracellular matrix (ECM) or other bioengineered material, syntheticbioabsorbable polymeric scaffolds, collagen, and combinations thereof.10. The method of claim 9, wherein said tissue scaffold includesnitinol.
 11. The method of claim 9, wherein said tissue scaffold isattached to said loops of said first side.
 12. The method of claim 1,wherein said intermediate joint is positioned so as to minimizedistortion to the septal tissue surrounding the defect.
 13. The methodof claim 1, wherein said intermediate joint is positioned at an angle θfrom said second side and wherein said angle θ is greater than 0 degreesand less than about 90 degrees.
 14. The method of claim 2, wherein saidfirst side comprises at least three adjacent loops havingradially-extending wire segments, the three adjacent loops beingattached at the intermediate joint.
 15. The method of claim 14, whereinsaid radially-extending wire segments of said at least three adjacentloops of each of said first and second sides are connected.
 16. Themethod of claim 15, wherein said radially-extending wire segments ofsaid at least three adjacent loops of said first side are welded. 17.The method of claim 14, wherein said first side comprises less than orequal to ten loops.
 18. The method of claim 1, wherein the intermediatejoint is selected from the group consisting of a weld, a solder, a tube,and a spring.